The present invention relates to a device for supporting a heavier hand-held tool, particularly a machine-driven tool such as a spot welding gun intended to be used for e.g. plate works, such as repairs of car bodies or the like, and optionally for supporting cables attached to said tool.
The present invention is applicable to a large variety of different, preferably heavy, hand-held tools, but in the following sections hereinbelow, it will mainly be described in relation to spot welding guns.
A spot welding gun is usable for resistance welding or spot welding, wherein two or several welding objects, are joint together in one or several points.
Resistance welding of this kind may be used for manufacture but more generally it is used for repairs, particularly of car bodies. Resistance welding is in this respect often the most suitable joining method, where it is applicable as regards accessibility. It is a fast and effective method, which provides for stronger welding joints with fewer welding spots than if a MIG-weld or the like is used. Resistance welding using a spot welding gun is furthermore harmless to the environment; for instance the flue gases are severely reduced. Furthermore, the method provides for a low heat release in the plate around the welding spot, which provides for a maintained corrosion resistance of zincified plate, and the thermal stresses in the structures are minimized.
The so-called welding parameters that may be varied during the welding comprise electrode pressure, welding current strength and time, cooling effect, cooling time and hold time.
One of the problems of using a spot welding gun is due to its heaviness, which may limit the use of it. Spot welding includes a number of different operations including positioning the spot welding gun at the objects to be welded, adjusting the electrodes to the point where it is desired to have the weld joint, and also sufficiently close to each other so that the stroke of the cylinder is xe2x80x9csufficientxe2x80x9d to attain necessary electrode pressure during welding. Further, the operations include activating compressed air to raise the electrode pressure, applying a welding voltage over the electrodes, holding the gun during the welding processing, turning off the voltage, lowering the electrode pressure and removing the gun.
While positioning the welding gun at the objects to be welded, it may be difficult to pass edges or other obstacles of the welding objects. Typically, this is solved in such a way that it will be possible to release or demount an electrode or an arm of the gun.
All these mentioned operations are to be performed while holding the spot welding gun in the hands. This is hard work for the user and will be tiring if no support is available.
JP 111156557 A (applicant: Toyota Auto Body Co Ltd) depicts a welding gun stand provided with an arm arrangement having an arm tip end to which a welding gun is suspended via a balancer or balancer reel. The arm arrangement permits movement of the arm tip end in the horizontal direction for increasing the moving-around range of the welding gun.
In WO 97/14540 (applicant: Atlas Copco Berema AB) a device for supporting hand-held machine-driven tools, is described. The device includes a harness structure to be carried on the back of a worker, said harness structure having a frame, a tube system and a balancer reel attached thereto. The tube system extends upwardly and forwardly and ends in front of and above the worker, and guides a line element, which in one end is attached to the balancer reel and in which other end the hand-held machine driven tool is suspended. The balancer reel has a setting spring for adjusting the is force exerted on the line element such that the tool is hung in a weight-balanced state.
The balancer reel may be of conventional design and comprises a reeling drum for the line element and a helical setting spring or may be of an improved kind wherein the tension of the spring is kept constant irrespective of the length to which the line element is drawn out. An explicit reference to such an improved balancer is given as U.S. Pat. No. 4,290,564 issued to Karlsson.
Said U.S. patent discloses a spring-operated reversably rotatable body having a conical surface on which a line element or similar can be wound, the body being connected to a coil spring which is stretched by the rotation of the body during winding of the line element. The conical structure of the body surface provides means by which the tensile force caused by the coil spring on the line element during rotation of the body will remain constant. The spring-operated body may further be provided with an adjustment screw for adjusting the shape of the body and thus the tensile force of the spring. It is mentioned that the invention is particularly useful in retractable safety belts to obtain a constant force in the belt strap during extension of the belt.
Thus, according to the prior art, there are needed complex and expensive balancer reels in known supporting devices for counter-acting the weight of a hand-held tool, such as e.g. a spot welding gun. Further, these balancers are bulky, and thus require much space, and they require adjustment of the tensile force.
It is an object of the present invention to provide a device for supporting a hand-held tool, particularly a machine-driven tool such as a spot welding gun intended to be used for e.g. plate works, such as repairs of car bodies or the like, which is lacking one or several of the problems which occurs using a supporting device according to the prior art.
Thus, it is an object to provide a device, which through an uncomplicated process enables or simplifies the use of a hand-held tool such as a spot welding gun.
A further object of the invention is to provide a device of the kind mentioned above, which is simple, compact, reliable and easy to manufacture.
Yet a further object the invention is to provide such a supporting device, which is easily modifiable to suit hand-held tools of various sizes and weights.
These and other objects are according to one aspect of the invention attained by a device for supporting a heavier hand-held tool comprising a tool stand provided with a support arm arrangement mounted thereon, and a constant force spring having a first end and a second end,
said first end of the constant force spring being attached to said support arm arrangement, and
said hand-held tool being hung from said second end of the constant force spring, wherein
the constant force of the spring is such that a user of the hand-held tool is relieved from at least a substantial portion of the weight of the tool, and
the drawn-out length of the spring is long enough to enable the tool to be hung in a plurality of different operation heights.
According to a further aspect of the invention there is provided a device for supporting a heavier hand-held tool, particularly a machine-driven tool such as a spot welding gun intended to be used for e.g. plate works, such as repairs of car bodies or the like, optionally with cables attached to it, comprising a tool stand provided with a support arm arrangement mounted thereon, a constant force spring having a first end and a second end, and a line element having a first end and a second end,
said first end of the constant force spring being attached to said support arm arrangement, and
said second end of the constant force spring being attached to said first end of the line element,
said hand-held tool being arranged to be suspended from said second end of the line element, wherein
the constant force of the spring is such that a user of the hand-held tool, during use, is relieved from at least a substantial portion of the weight of the tool, and optionally of the cables attached to it, and
the drawn-out length of the spring is long enough to enable the tool to be suspended in a plurality of different operation heights.
According to still a further aspect of the invention there a-s provided a device for supporting cables attached to a heavier hand-held tool, particularly a machine-driven tool, such as a spot welding gun intended to be used for e.g. plate works, such as repairs of car bodies or the like, comprising a tool stand provided with a support arm arrangement mounted thereon, a constant force spring having a first end and a second end, and a line element having a first end and a second end,
said first end of the constant force spring being attached to said support arm arrangement, and
said second end of The constant force spring being attached to said first end of the line element,
said cables attached to the hand-held tool being arranged to be suspended from said second end of the line element, wherein
the constant force of the spring is such that a user of the hand-held tool, during use, is relieved from at least a substantial portion of the weight of the cables attached to it, and
the drawn-out length of the spring is long enough to enable the cables to be suspended in a plurality of different operation heights.
An advantage of the supporting devices according to the present invention is that they are readily and easily manufactured to a relatively low cost.
A further advantage of the inventive devices are that they are simple and provide for a reliable and effective weight-balancing function.
More advantages and features of the invention will be apparent from the description below.